Patients between 9 and 18 months of age having the diagnosis of osteogenesis imperfecta will be randomly assigned to standard medical rehabilitation or experimental bracing and ultralight custom molded long leg brace and a prescribed physical therapy program. Patients will be assigned to a treatment group according to a randomized schedule, 10 in each group. The braced group will be evaluated every 3 months for proper fit, and review of physical therapy. Both groups will be evaluated yearly for size, musculature, and fracture history. Observers will record clinical data and evaluate the patient for height, weight and compliance with the study.